Last week is expected to be one for the record books for the Hawaiian islands of O’ahu and Kaua’i.

While thunderstorms at this time of year are not uncommon, it is the strength and severity at which they hit that caused the governor of Hawaii to declare states of emergency for these two islands.

A blocking weather pattern in the Pacific has forced Hawaii to endure stronger and more frequent thunderstorms in the last seven days. For example, in a 45 minute period on Friday morning, hail the size of golf balls fell over O’ahu during one of these storms. Tom Birchard, senior meteorologist at the National Weather Service (NWS) in Honolulu, said that not only is it highly unusual to have hail over Hawaii, but that the size of the hail will likely break previous records.

The NWS has also been compiling the rain totals for the week and expects that these numbers will break records as well. On the island of Kaua’i, the towns of Kapahi and Hanalei saw 82 and 116 centimetres of rain respectfully in a seven day period, while O’ahu picked up 100 centimetres. These amounts are 10 to 15 times higher than what would normally be seen this time of year.

Tourists have been stranded in their hotels as flights have been cancelled, while on the ground landslides have closed some of the highways.

On Friday, a waterspout made landfall on the eastern shore of O’ahu, then became a rare tornado. Rated as an EF-0, the weakest possible strength given to tornadoes, the twister was still strong enough to tear holes in roofs and down trees along a two kilometre path.

For Hawaii, tornadoes tend to be a rarity. Only 39 have been reported for the island state since 1950, with an average of one tornado every 1 ½ years.

For the next few days, there is still the risk of showers, but by midweek skies are expected to clear.